The primary objective of the research plan continues to be the elucidation of relationships between the conformations of prostaglandins, prostacyclins and thromboxanes and their biological functions. To this end we have continued to pursue our single crystal X-ray diffraction studies of PG-related molecules and have begun studies of 15-hydroxyprostaglandin dehydrogenase, the major metabolizing enzyme of the PG family. Our goal this coming year is to crystallize PGDH and a number of heavy atom derivatives of PGDH for X-ray diffraction studies. To accomplish our goal we will continue to work on improved techniques for PGDH isolation and purification. In the small molecule studies area we plan to continue to examine the structures of prostacyclin and thromboxane analogs in order to fill out our examination of the whole family of compounds.